Measuring instrument.



H.. MILLER.

MEASURING INSTRUMENT. APPLICATION FILED JAN. 10, 1909.

1,120,838, Patented Dec. 15,1914.

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' the movable elements in the zero or other.

UNITED STATES PATENT OFFICE,

HENRY MILLER, oE-EAsr ORANGE, NEW. JERSEY, ASSIGKOE'ZBY MESNE AssIGN- -1VEN'IS, T0 WESTINGHOUSE ELECTRIC & mANuEAornaINecemANY, 01 EAST. rrrrsnunen, rENNsYLvANIA, A conronA'rIoN or PENNSYLVA IA.

MEASURING INSTRUMENT.

Specification of Letters Patent.

Patented Dec.'15, 1914..

To all whom it may concern) Be it known that I, HENIRYV MILL R, 'aQcitizen of the United States,' and a resident of East Orange, in the county of Essex" and State of New Jersey, have invented a new and useful Improvement in .Measuring Instruments, of which the following is a specification,

My invention relates to measuring instruments, and it has for its object to provide simple and economical means whereby the torque exerted by a helical or spi'ral spring for a given deflection thereof may be readily and accurately determined.

In the construction of electrical and other measuring instruments of the indicating type, spiral springs are frequently employed for the purpose of normally maintaining predetermined positions and for opposing torques to those exerted between the stationary and movable members of the instruments. In the manufacture of such instrument's, it is usually desirable that the torque exerted by a spring for a given deflection thereof shall be known before the spring'is placed in the instrument, and it is the .object of the present invention to provide an instrument whereby the torque exerted by a spring, for a given deflection thereof, may be determined with expedition and precision.

Figure 1 of the accompanying; drawings is a face view of an instrument constructed in accordance with my invention, and Fig. 2 is a view, in transverse section, of the instrument shown in Fig. 1.

' The operating parts of the instrument are inclosed within a case comprising a wooden base 1 and a cylindrical sheet metal side piece 2, upon the upper edge of which rests an annular plate of glass 3, a ring 4 that extends downwardly over the upper end of clamping the said plate in position. Susthe side piece 2 and is secured thereto by means of screws 5. being provided for pended from the plate 3 by means of bolts (Sis a dial plate 7 having a graduated scale 8 and areflecting surface 9 upon its upper fac andlsecured to the middle of the plate is a down wardly extending lug 10 which is internally screw-threaded for the reception of a screw 11 having a concave bearing jewel 12 in its upper end. The jewel 12 is provided with a ball 13,--upon which bears anotherconcave jewel 14; mounted in the lower end of a vertical shaft 15 having a pointer 16 adapted to, move over the scale'8 and the mirror'9.- I,

vSecured at its inner end to shaft 15 is a spiral spring 17, the outer endofwhieh is secured to a stationary post 18, the said spring serving tor normally maintain the pointer 16 directly over the zeromark of the scale 8. ,r

Within the hpening in the annular plate 3 is a bushing 19 having a-fiange 20 that extends outwardly over the upper face of the plate. and is provided upon its upper face with a scale 21 that maybe graduated in degrees, as shown, or in any other desired J units, the said bushing being held stationary by means of a screw 22 that extends upwardly through the plate 3. The bushing 19 serves as a bearing for a rotatable member comprising another flanged'bushing 23 and a plate 24 that is secured, by means of tap-screws 25, to the upper end of the bushing 23, the plate 24: being provided with an arm 26 having a projection 27 the straight radial edge of which serves as an index to coiiperate with the scale 21. The arm 26 is also provided witha button or handle 28 whereby the plate 24 and the remainder of the movable member may be adjusted in position, and-with a pointer 29 that extends over the scale 8 and the mirror 9. c

Screw-threaded into the bushing 23 1s a supporting member or bushing 30 for a ring or annular shaped jewel 31, said jewel serv- I ingas an upper bearing for the "shaft 15 which projects through itand through and above the plate 24.

The shaft 15 is provided, at its outer end, with a flanged collar 32 and upon said collar is supported another flanged collar from which a shaft 34, of anydeslred dlameter, projects upwardly," the said collars being caused to rotate together by means of a dowel pin 35'that extends upwardly from the flange of the collar32- Secured to; the upper face=oftheplate 2t,

the provision of the slot- 37.

In utilizing the instrument, the inner end of a spring 42 of unknown calibration is rigidly clamped to a bushing 44 on the shaft 34 by means of a set-screw 43. In order to adapt the instrument for use in determining the calibration of springs that are mounted upon bushings of different internal diameters, a plurality of collars 33 having shafts 34 of diflerent diameters maybe provided to accompany the instrument.- With the radial edge of the projection 27 registering with the zero mark of the scale 21 and the pointers l6 and 29 registering with the zero mark of the scale 3,., the outer end of the spring 42 is then clamped to the post 39 by means of the block 40 and the thumb-screw 41. If the spring 42 is then deflected by moving the arm 26 until the index 27 has been moved a number of degrees over the scale 21, the torques exerted by the pointer 16 will indicate, upon the scale 8, the amount of torque exerted by each spring, the scale 8 having previously been graduated in any desired units, such, for instance, as centimeter grams. Thus, the torque exerted by the spring 42 for a given deflection may be read directly upon the scale 8 and the torques for any desired number of deflections may be readily determined. For springs of different radii, the bracket 38 may be adjusted in a radial direc: tion.

There are. several methodsof calibrating I the unknown spring. One method provides that the calibration of the ln own spring must be plotted between torques and deflectionsl The curve between the torques as measured by pointer 16 and the deflections indicatedby indicator 27 is plotted on the same sheet of paper, the deflections for the same torques are subtracted and that value plotted for each torque, that is the calibration curve of the unknown spring. Another method makes use of the pointer 29 in that the ratio of the deflection of the pointer 29 is to the deflection of the pointer 16 as the deflection of the indicator 27 is to a, then the deflection of indicator 27 minus cc-is the deflection of the unknown spring for the deflcction as indicated by pointer 16.

I claim as my invention:

1. In an instrument, the combination with a shaft,an indicator carried thereby, and a scale with which the indicator coiiperates, of a spring of known calibration adapted to normally maintain the shaft in a predetermined position,

' shaft with one of exerted .by the spring the springs 42 and 17 will be opposed and balanced, and,

means for mounting a spring ofunlmown calibratlon upon the member rotatable about the shaft and havng one end of the spring of unknown calia spring of known calibration, of means for oppos ng thereto a spring of unknown cali bration, and means includingthe spring of known calibration for determining the force of unknown calibraits ends secured thereto, a

tion for: apredetermined deflection thereof. 7

3. In an instrument, the combination with means for opposing'the force exerted by a spring of known calibration by that of a spring of unknown calibration, and means including the spring of known calibration for indicating force. 4. In an instrument, the combination with means foropposing the force exerted by a spring of known calibration by that of a spring of unknown calibratiom means including the spring of known calibration for indicating the value of the opposing forces, and means for subjecting thespring of. unknown calibration to different degrees of deflection.

5. In an instrument, the combination with a shaft and two concentric scales, of indicators for the respective scales, a spring of known calibration interposed between a stationary part and one of the indicators, means for interposing a spring of unknown calibration between the two indicators and means including thespring of bration for adjusting one of said indicators to determine the torque exerted by the spring of unknown calibration. f 6. In an instrument, the combination with two annular scales, and a sh aft concentrically disposedwith reference to said scales, of an indicator mounted on said shaft to cooperate with one of said scales, a spiral spring of known calibration having one end attached to said shaft and its other end held stationary, a manually adjustable indicator mounted independently of the shaft to cooperate with the other scale, and a spiral spring of unknown calibration having one end attached to the shaft and its other end connected to the manually adjustable indicator.

7. In an instrument, the combination with a spiral spring of known calibration, of means for rotatively spiral spring of unknown calibration, and means including the spring of known calibration for-determining the torque exerted predetermined deflection thereof.

the value of the opposing known caliopposing thereto a 8. In an instrument, the combination with means for rotatively opposing the torques exerted by a spiral spring of known calibration and a spiral spring of unknown calibration, and means including the spring of known calibration for indicating the value of the opposing torques.

9. In an instrument, the combination with means for rotatively opposing the torques exerted by a spiral spring of knowncalibration and a spiral spring of unknown calibration, means including the spring of known calibration for indicating the value of the opposing torques, and means for subjecting the spring of unknown calibration to different degrees of deflection.

10; In an instrument, the combination with means for rotatively opposing the torques exerted by a spiral spring of known calibration and a spiral spring of unknown calibration, and an indicator actuated by said springs for indicating the value of the opposing torques.

'11. In an instrument, the combination with means for rotatively opposing the torques exerted by a-spiral spring of knowncalibration and a spiral spring of unknown calibration including means for adapting the instrument to unknown-springs of various diameters, and an indicator actuated by said springs for indicating the value of the opposing torques.

In testimony whereof, I have hereunto Enwn. W. CAMPBELL.

Copies 01 this patent may be obtained for five cents each, by addressing the "Commissioner 0! Patents,

' Washington, D. G." 

